This invention relates to flexible electro-optic displays, in particular to displays based on a structure built of flexible fibers.
An electro-optic display is a device designed to change its optical state when some kind of electric or electromagnetic field is applied to it. A visible image on such displays is formed from a plurality of display elements including an electro-optically active (EOA) substances. The term xe2x80x9cEOA substancexe2x80x9d denotes any substance that changes its color, transparency, reflection or other optic properties, or capable of emitting light, when subjected to changes of electric or electromagnetic field, and thereby suitable for displaying images. Flexible electro-optic displays may be made of flexible polymer films, where the EOA substance and patterns of electrodes are laid in thin layers over a polymer substrate, or may be based on flexible fibers or strips woven or knitted into fabric or textile material where the electrodes are in the constituent fibers. Woven displays have certain advantages since they may be produced using known weaving techniques which do not limit their length. Woven displays are more flexible and robust than integral film displays.
U.S. Pat. No. 5,962,967 and JP 2001-034195 disclose woven displays made of two sets of transverse fibers including a longitudinal conductor and a coating of light-emitting or other EOA substance. An individually controllable display element (pixel) is formed at each junction where a fiber of one set overlaps a fiber of the other set. The visible images on such displays are formed from a plurality of pixels. Understandably, the optically active (luminous) zones in such pixels are of the size of the fiber diameter.
U.S. Pat. No. 3,803,437 discloses a display comprising a set of conductive wires interwoven with a transverse set of insulating fibers, and covered with a layer of phosphor. Electric voltage is applied between each two adjacent conductors and a continuous luminous surface is obtained, without display elements. In this structure, the space between the conductive wires must be of predetermined width depending on the nature of the phosphor.
U.S. Pat. No. 3,571,647 discloses a woven display comprising a carrying non-conductive fabric impregnated with a phosphor, a first (common) electrode in the form of a flexible conductive layer laid at the back of the fabric, and second electrodes in the form of insulated wires sewn into the fabric. The second electrodes may be sewn in various designs to form display elements of a static image or picture. The luminous zone of each element is in a narrow vicinity of the insulated wire stitches.
In accordance with the present invention, there is provided an electro-optical display comprising: a plurality of fibers, preferably woven or knitted, some of them including conductive wires. The fibers form a flexible carrying network with cells defined therebetween. A layer of EOA substance fills the cells, and a first conductive layer covers one side of the carrying network. This conductive layer is transparent or translucent and is in electric contact with the conductive wires. A second conductive layer covers the other side of the network but is insulated from the conductive wires. An electrooptically active zone (EOA zone) is formed between the first and the second conductive layer, where the conductive wires serve to power the first transparent conductive layer. The second conductive layer may be also transparent.
According to one embodiment of the present invention, the EOA substance is filling the carrying network cells in separated spots or in spots of different electro-optic properties. These spots constitute display elements that may be controlled en ensemble and thus form a so-called static visible image.
According to another embodiment of the present invention, the second conductive layer is laid on the network in separated spots, thereby dividing the EOA zone into individually controllable display elements. Thus a dynamic or animated visible image may be formed.
According to a further embodiment of the present invention, the fibers of the display are organized in two or more sets. The first set includes fibers with conductive wires which run generally parallel to each other. The first transparent conductive layer is laid in separated longitudinal strips parallel to the fibers of the first set. Each strip is in electric contact with one or more conductive wires of the first set, but each conductive wire is in contact with only one strip. The second conductive layer is laid in separated parallel strips transverse to the longitudinal strips, thereby forming a dynamic matrix of individually controllable display elements or pixels, each pixel being defined in the overlapping area between a longitudinal strip and a transverse strip. The EOA substance in each pixel may have different electro-optic properties. In this way, an RGB or CMYK color display may be particularly obtained.
According to a still further embodiment of the present invention, an electro-optical display may have in parts thereof a dynamic matrix of individually controllable pixels, in other parts thereofxe2x80x94dynamic or animated images, and in still other parts of the same display-static images.
According to a last embodiment of the present invention, an electro-optical display may comprise a plurality of fibers including longitudinal conductive elements arranged in a flexible carrying network, EOA substance filling the cells, and a conductive layer covering one side of the network and insulated from the conductive elements. In this case EOA zones are formed in xe2x80x9cpocketsxe2x80x9d adjacent to the conductive elements and the conductive layer.
The electro optic displays of the present invention are based on a cellular network with conductive layers on both sides thereof which presents a robust and flexible structure reliably accommodating the EOA substance. In these displays, the entire mass of the EOA substance may be utilized for producing optical effects, and in one display, static pictures may be combined with dynamic images such as running text or animation. In woven displays using high voltage, such as electroluminescent (EL) displays, electric breakdowns arising from defects in coating layers of the conductive fibers may be avoided. Other important advantages of the present invention are that the carrying network structure may be produced by well known efficient weaving or knitting methods, the transparent conductive layer may be made of polymers of limited conductivity, and display elements of arbitrary shape and size or matrix pixels can be obtained by printing techniques.